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Hematopoietic stem and progenitor cell (HSPC)-based gene therapy (GT) requires the collection of a large number of cells. While bone marrow (BM) is the most common source of HSPCs in pediatric donors, the collection of autologous peripheral blood stem and progenitor cells (PBSCs) is an attractive alternative for GT. We present safety and efficacy data of a 10-year cohort of 45 pediatric patients that underwent PBSC collection for backup and/or purification of CD34+ cells for ex vivo gene transfer. Median age was 3.7 years and median weight 15.8 kg. After mobilization with lenograstim/plerixafor (n=41) or lenograstim alone (n=4), and 1-3 cycles of leukapheresis, median collection was 37 x106 CD34+ cells/kg. The procedures were well tolerated. Patients that collected ≥7 and ≥13 x106 CD34+ cells/kg in the first cycle had pre-apheresis circulating counts of at ≥42 and ≥86 CD34+ cells/μL respectively. Weight-adjusted CD34+ cell yield was positively correlated with peripheral CD34+ cell counts, and influenced by female gender, disease and drug dosage. All patients received a GT product above the minimum target, ranging from 4 to 30.9 x106 CD34+ cells/kg. Pediatric PBSC collection compares well to BM harvest in terms of CD34+ cell yields for the purpose of GT, with a favorable safety profile.

Background. Median age of occurrence of acute myeloid leukemias (AML) and myelodisplastc syndromes (MDS) is 65 years and older. Nevertheless, the use of allogeneic stem cell transplant (allo-HCT) has been historically limited to younger population, namely due to excess in non-relapse-mortality (NRM) in olders. Methods. In the present study, we analyzed all consecutive patients aged ≥ 65y diagnosed with AML (71, 81%) or MDS (19, 19%) who received transplants from adult donors at our center from January 2005 to December 2019. Results. Median age was 68.29y (65.02-76.54), 26pts (29%) aged ≥ 70y. Thirty-three (37%) pts received a HLA-matched donor. Conditioning regimen was myeloablative in 46pts (51%). The 3-year overall survival (OS) was 53+/-6%, and disease free survival (DFS) 45+/-6% (Figure 1). Day-100 and 3-year NRM was 17+/-2% and 29+/-2%, respectively. The 3-year CI of relapse was 22+/-2%. Day-100 CI of aGvHD was 21+/-2% for grade II-IV, 14+/-1% for grade III-IV. The 3-year CI of cGvHD was 35+/-3%, extensive 20+/-2%. In multivariate analysis, the Karnofsky Performance Status (KPS) < 90% was associated with lower OS (HR: 2.999, CI: 1.477- 6.691; p=0.002), DFS (HR: 3.155, CI: 1.593 - 6.250; p=0.001) and higher NRM (HR: 2.997, CI: 1.344-6.682; p=0.041). HCT-CI ≥ 3 was also associated with higher NRM (HR: 2.949, CI: 1.166-7.462, p=0.022,). Diagnosis of MDS and receiving a matched donor with PTCy were associated with longer OS (HR: 0.3440, CI: 0.1029-0.915; p=0.033; HR: 0.197, CI: 0.042-0.934; p=0.041).Conclusions. Age alone should not limit transplant eligibility for AML and MDS. KPS and HCT-CI proved to be useful for patient selection among the elderly. The use of HLA-matched donors with PTCy improved OS compared to ATG in our consecutive series.

IntroductionAllogeneic stem cell transplantation survivors are at a relevant risk of developing chronic GvHD (cGvHD), which importantly affects quality of life and increases morbidity and mortality. Early identification of patients at risk of cGvHD-related morbidity could represent a relevant tool to tailor preventive strategies. The aim of this study was to evaluate the prognostic power of immune reconstitution (IR) at cGvHD onset through an IR-based score.MethodsWe analyzed data from 411 adult patients consecutively transplanted between January 2011 and December 2016 at our Institution: 151 patients developed cGvHD (median follow-up 4 years). A first set of 111 consecutive patients with cGvHD entered the test cohort while an additional consecutive 40 patients represented the validation cohort. A Cox multivariate model for OS (overall survival) in patients with cGvHD of any severity allowed the identification of six variables independently predicting OS and TRM (transplant-related mortality). A formula for a prognostic risk index using the β coefficients derived from the model was designed. Each patient was assigned a score defining three groups of risk (low, intermediate, and high).ResultsOur multivariate model defined the variables independently predicting OS at cGvHD onset: CD4+ >233 cells/mm3, NK 3, IgA 3/mm3. Low-risk patients were defined as having a score ≤3.09, intermediate-risk patients >3.09 and ≤6.9, and high-risk patients >6.9. By ROC analysis, we identified a cut-off of 6.310 for both TRM and overall mortality.In the training cohort, the 6-year OS and TRM from cGvHD occurrence were 85% (95% CI, 70-92) and 13% (95% CI, 5-25) for low-risk, 64% (95% CI, 44-89) and 30% (95% CI, 15-47) for intermediate-risk, 26% (95% CI, 10-47), and 42% (95% CI, 19-63) for high-risk patients (OS pThe validation cohort confirmed the model with a 6-year OS and TRM of 83% (95% CI, 48-96) and 8% (95% CI, 1-32) for low-risk, 78% (95% CI, 37-94) and 11% (95% CI, 1-41) for intermediate-risk, 37% (95% CI, 17-58), and 63% (95% CI, 36-81) for high-risk patients (OS p = 0.0075; TRM p = 0.0009).ConclusionsIR score at diagnosis of cGvHD predicts GvHD severity and overall survival. IR score may contribute to the risk stratification of patients. If confirmed in a larger and multicenter-based study, IR score could be adopted to identify patients at high risk and modulate cGvHD treatments accordingly in the context of clinical trial.

BackgroundCommon variable immunodeficiency (CVID) is the most frequent primary antibody deficiency. A significant number of CVID patients are affected by various manifestations of immune dysregulation such as autoimmunity. Follicular T cells cells are thought to support the development of CVID by providing inappropriate signals to B cells during the germinal center (GC) response.ObjectivesWe determined the possible role of follicular helper (Tfh) and follicular regulatory T (Tfr) cells in patients with CVID by phenotypic, molecular, and functional studies.MethodsWe analyzed the frequency, phenotype, transcriptome, and function of circulating Tfh cells in the peripheral blood of 27 CVID patients (11 pediatric and 16 adult) displaying autoimmunity as additional phenotype and compared them to 106 (39 pediatric and 67 adult) age-matched healthy controls. We applied Whole Exome Sequencing (WES) and Sanger sequencing to identify mutations that could account for the development of CVID and associate with Tfh alterations.ResultsA group of CVID patients (n=9) showed super-physiological frequency of Tfh1 cells and a prominent expression of PD-1 and ICOS, as well as a Tfh RNA signature consistent with highly active, but exhausted and apoptotic cells. Plasmatic CXCL13 levels were elevated in these patients and positively correlated with Tfh1 cell frequency, PD-1 levels, and an elevated frequency of CD21loCD38loautoreactive B cells. Monoallelic variants inRTEL1, a telomere length- and DNA repair-related gene, were ideintified in four patients belonging to this group. Lymphocytes with highly shortened telomeres, and a Tfh signature enriched in genes involved in telomere elongation and response to DNA damage were seen. Histopathological analysis of the spleen in one patient showed reduced amount and size of the GC that, unexpectedly, contained an increased number of Tfh cells.ConclusionThese data point toward a novel pathogenetic mechanism in a group of patients with CVID, whereby alterations in DNA repair and telomere elongation might be involved in GC B cells, and acquisition of a Th1, highly activated but exhausted and apoptotic phenotype by Tfh cells.

BACKGROUND. The human bone marrow (BM) niche contains a population of mesenchymal stromal cells (MSCs) that provide physical support and regulate hematopoietic stem cell (HSC) homeostasis. β-Thalassemia (BT) is a hereditary disorder characterized by altered hemoglobin beta-chain synthesis amenable to allogeneic HSC transplantation and HSC gene therapy. Iron overload (IO) is a common complication in BT patients affecting several organs. However, data on the BM stromal compartment are scarce. METHODS. MSCs were isolated and characterized from BM aspirates of healthy donors (HDs) and BT patients. The state of IO was assessed and correlated with the presence of primitive MSCs in vitro and in vivo. Hematopoietic supportive capacity of MSCs was evaluated by transwell migration assay and 2D coculture of MSCs with human CD34+ HSCs. In vivo, the ability of MSCs to facilitate HSC engraftment was tested in a xenogenic transplant model, whereas the capacity to sustain human hematopoiesis was evaluated in humanized ossicle models. RESULTS. We report that, despite iron chelation, BT BM contains high levels of iron and ferritin, indicative of iron accumulation in the BM niche. We found a pauperization of the most primitive MSC pool caused by increased ROS production in vitro which impaired MSC stemness properties. We confirmed a reduced frequency of primitive MSCs in vivo in BT patients. We also discovered a weakened antioxidative response and diminished expression of BM niche–associated genes in BT-MSCs. This caused a functional impairment in MSC hematopoietic supportive capacity in vitro and in cotransplantation models. In addition, BT-MSCs failed to form a proper BM niche in humanized ossicle models. CONCLUSION. Our results suggest an impairment in the mesenchymal compartment of BT BM niche and highlight the need for novel strategies to target the niche to reduce IO and oxidative stress before transplantation. FUNDING. This work was supported by the SR-TIGET Core grant from Fondazione Telethon and by Ricerca Corrente.

Post-transplantation cyclophosphamide (PTCy) has emerged as a promising graft-versus-host-disease (GVHD) prophylaxis in the setting of allogeneic hematopoietic stem cell transplantation (HSCT) from haploidentical donors and more recently in matched donor transplants. Herein, we describe our real-life experience on 249 adult patients undergoing allogeneic HSCT, from HLA-matched related (MRD), HLA-matched unrelated (MUD), or mismatched related donors (MMRD). Patients received unmanipulated peripheral blood stem cells (PBSCs), using a GVHD prophylaxis with PTCy and sirolimus. Mycophenolate mofetil was added in MUD or MMRD. In the HLA-matched donor group (MRD, n = 48, MUD, n = 50), the cumulative incidence of grades II-IV and III-IV acute GvHD was 23% and 9% at 100 days, respectively. The cumulative incidence of chronic GvHD was 25% at 2 years, severe only for 5% of the patients. The cumulative incidences of relapse and transplant-related mortality (TRM) were 31% and 9% at 2 years, respectively. The 2-year overall survival (OS) was 72% and progression-free survival (PFS) 60%; the composite endpoint of GvHD/relapse-free survival (GRFS) was 52% at 2 years. In the haploidentical donor group (n = 151), we documented a cumulative incidence of grades II-IV and III-IV acute GVHD of 35% and 20% at 100 days, respectively, and a cumulative incidence of chronic GvHD of 39% at 2 years. We observed severe chronic GVHD in 15% of the patients. The cumulative incidence of relapse and TRM was 32% and 25% at 2 years, respectively. The 2-year OS was 48%, whereas PFS was 43%; GRFS was 28% at 2 years. However, more patients in the haploidentical group presented high/very high disease risk index (DRI) and higher HCT-comorbidity index. In patients classified in the low-intermediate DRI, 2-year GRFS was 53% in MRD, 65% in MUD, and 46% in haploidentical HSCT (P = .33). Sirolimus-PTCy platform deserves further investigation as an alternative to calcineurin-inhibitor–based GVHD prophylaxis for all donor sources. In patients presenting a low-intermediate DRI, this strategy translates in relevant survival independently from the transplant source.

Hematopoietic stem cells (HSCs) are regulated by signals from the bone marrow (BM) niche that tune hematopoiesis at steady state and in hematologic disorders. To understand HSC-niche interactions in altered nonmalignant homeostasis, we selected β-thalassemia, a hemoglobin disorder, as a paradigm. In this severe congenital anemia, alterations secondary to the primary hemoglobin defect have a potential impact on HSC-niche cross talk. We report that HSCs in thalassemic mice (th3) have an impaired function, caused by the interaction with an altered BM niche. The HSC self-renewal defect is rescued after cell transplantation into a normal microenvironment, thus proving the active role of the BM stroma. Consistent with the common finding of osteoporosis in patients, we found reduced bone deposition with decreased levels of parathyroid hormone (PTH), which is a key regulator of bone metabolism but also of HSC activity. In vivo activation of PTH signaling through the reestablished Jagged1 and osteopontin levels correlated with the rescue of the functional pool of th3 HSCs by correcting HSC-niche cross talk. Reduced HSC quiescence was confirmed in thalassemic patients, along with altered features of the BM stromal niche. Our findings reveal a defect in HSCs in β-thalassemia induced by an altered BM microenvironment and provide novel and relevant insight for improving transplantation and gene therapy approaches.

Variation in clinical practice affects veno-occlusive disease management, mainly in patients who undergo allogeneic hematopoietic stem cell transplantation. Disputes about diagnostic criteria, treatment, and prophylaxis, due to the lack of high-quality data, are at the base of this variability. With the aim of limiting inconsistency in clinical care, thus improving both patient outcomes and data collection reliability, the Italian Society of Stem cell transplant (Gruppo Italiano Trapianto Midollo Osseo e Terapia Cellulare) launched a collaborative effort to formulate recommendations based on integration of available evidence and expert's consensus. A systematic method, according to US National Institute of Health guidelines and Italian National System for Guidelines, was used. Twenty-nine recommendations were approved with a strong (20) or weak (9) level of agreement, while 26 were rejected. In particular, the panel pointed out the need to achieve an early diagnosis, encouraging the adoption of European Society for Blood and Marrow Transplantation criteria and the prompt use of ultrasonography. Moreover, our experts strongly recommended in favor of prophylactic use of ursodeoxycholic acid. As soon as a veno-occlusive disease diagnosis is established, treatment with defibrotide should be started for at least 21 days. A number of areas of uncertainty, particularly concerning risk stratification and use of diagnostic tools such as elastography has been identified and discussed.

The bone marrow (BM) niche regulation and interactions with hematopoietic stem cells (HSC) have been extensively studied in steady state conditions and malignancies, but are still underexplored in hematological inherited disorders. We provided the first demonstration of impaired HSC function caused by an altered BM niche in a non-malignant disease, beta-thalassemia (BT) (Aprile et al., Blood 2020). BT is a globally widespread congenital hemoglobin disorder, resulting in severe anemia, ineffective erythropoiesis and multi-organ secondary complications, including bone alterations. Correction of the genetic defect is achieved by transplantation of HSC from healthy donors or autologous HSC from patients upon gene therapy. Since the quality and the engraftment of HSC depend on the BM microenvironment, niche-HSC crosstalk plays a crucial role for transplantation outcome. During the analysis of different components of the niche, we found reduced bone density in BT th3 mice, along with a defective HSC supporting activity by the BM stromal niche. Interestingly, osteoporosis is a constant hallmark in BT patients. We investigated the mechanisms underlying bone and HSC niche defects focusing on the role of fibroblast growth factor-23 (FGF-23), a hormone mainly secreted by osteocytes, but also by erythroid cells, which negatively modulates bone metabolism. Since FGF-23 is stimulated by the anemia-related factor erythropoietin (EPO), we hypothesized that the high EPO levels in BT might contribute to increase FGF-23, potentially affecting bone and BM niche homeostasis. We found high levels of circulating FGF-23 in th3 mice (wt vs. th3: 290.5±27.3 vs. 1823±136.1 pg/ml, p To provide proof of concept data on the contribution of FGF-23 to BT bone and stromal niche alterations, we inhibited FGF-23 signaling. In vivo administration of FGF-23 blocking peptide rescued the trabecular bone density in th3 mice (th3 vs. th3+FGF23inh: 138.2±4.9 vs. 166.9±5.2 mg/cm 3, p Evidence in BT patients showed negative correlations between FGF-23 levels and markers of bone homeostasis (e.g. osteocalcin R 2=0.88, p Our findings uncover an underexplored role of FGF-23 in bone and BM niche defects in a primary anemia, as a condition of chronic EPO stimulation, and propose FGF-23 as the missing link between hematopoiesis and bone regulation. The inhibition of FGF-23 signaling might provide a novel strategy to ameliorate bone compartment and restore HSC-BM niche interactions in BT by a 'two birds with one stone' approach, with a potential translational relevance in improving HSC transplantation and gene therapy. Disclosures Cappellini: Celgene: Consultancy, Research Funding; Vifor: Consultancy; La Jolla: Research Funding; Protagonist Therapeutics: Research Funding; IONIS Pharmaceuticals: Consultancy; CRISPR Therapeutics: Research Funding; Novartis: Consultancy, Honoraria, Research Funding.

Febrile neutropenia and sepsis are common and life-threatening complications in hematological diseases. This study was performed retrospectively in 514 patients treated for febrile neutropenia at our institute, to investigate the clinical usefulness of a molecular tool, LightCycler® SeptiFast test (SF), to promptly recognize pathogens causing sepsis in hematological patients. We collected 1837 blood samples of 514 consecutive hematological patients. The time of processing is short. Overall, 757 microorganisms in 663 episodes were detected by molecular test and standard blood cultures (BC): 73.6% Gram-positive bacteria, 23.9% Gram-negative bacteria, and 2.5% fungal species. This large analysis demonstrated a significant episode-to episode agreement (71.9%) between the two methods, higher in negative samples (89.14%), and a specificity of 75.89%. Clinical variables that gave a statistically significant contribution to their concordance were absolute neutrophil count, ongoing antimicrobial therapy, timing of test execution, and organ localization of infection. The large analysis highlights the potential of molecular-based assays directly performed on blood samples, especially if implementing the detection of antibiotic resistance genes, which was lacking in the used study.

Although it is considered a relatively rare disorder, veno-occlusive disease (VOD) is one of the main causes of overall, non-relapse mortality associated with haematopoietic stem cell transplantation (HSCT). This article, based on the consensus opinion of haemato-oncology nurses, haemato-oncologists and pharmacists from both adult and paediatric services at the VOD International Multi-Disciplinary Advisory Board at the European Society for Blood and Marrow Transplantation (EBMT) meeting, Istanbul, 2015, aims to explore the multidisciplinary approach to care for the management of VOD, with an emphasis on current challenges in this area. The careful monitoring of HSCT patients allows early detection of the symptoms associated with VOD and timely treatment, ultimately improving patient outcomes. As part of a multidisciplinary team, nurses have an essential role to play, from pretransplant assessment to medical management and overall care of the patient. Physicians and pharmacists have a responsibility to facilitate education and training so that nurses can work effectively within that team.

Background: Although the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) has dramatically improved in the past decade, it is still compromised by transplant-related mortality (TRM), mainly caused by Graft-vs. -Host Disease (GvHD). Methods: We conducted a prospective observational study to ascertain the potential of serum interleukin-6 (IL6) levels, measured before conditioning and 7 days after allo-HSCT, in predicting acute GvHD, TRM and survival after allo-HSCT with Post-Transplant Cyclophosphamide (PT-Cy) based GvHD prophylaxis. Results: Between April 2014 and June 2017, we collected samples from 166 consecutive allo-HSCT patients. By ROC analysis, we identified a threshold of 2.5 pg/ml for pre-transplant IL6 and 16.5 pg/ml for post-transplant IL6. Both univariate and multivariate analyses confirmed the ability of high baseline IL6 levels to predict worse OS (HR 4.3; p < 0.01) and grade II–IV acute GvHD (HR 1.8; p = 0.04), and of high post-transplant IL6 to identify patients with worse OS (HR 3.3; p < 0.01) and higher risk of grade II–IV (HR 5; p < 0.01) and grade III–IV acute GvHD (HR 10.2; p < 0.01). In multivariate analysis, both baseline (HR 6.7; p < 0.01) and post-transplant high IL6 levels (HR 3.5; p = 0.02) predicted higher TRM. Conclusions: IL6 may contribute to the risk stratification of patients at major risk for aGvHD and TRM, potentially providing a window for additional prophylactic or preemptive strategies to improve the quality of life in the early post-transplant phase and the outcome of allo-HSCT.

BACKGROUND: Allogeneic hematopoietic stem-cell transplantation (allo-HSCT) is increasingly used to treat a wide range of non-malignant disorders. However, the optimal strategy to be employed for GvHD prevention remains a matter of debate. In particular, the use of ATLG for the prevention of immune-mediated complications in patients transplanted from a matched-related donor (MRD) is still controversial. In the matched unrelated donor (MUD) setting, there is retrospective evidence that Rituximab used as prophylaxis of EBV viremia may protect from acute GvHD (aGvHD) development, but the clinical benefit of pre-transplant Rituximab has never been assessed in prospective randomized studies. METHODS: We conducted a multicentre, randomized, open-label, trial (NCT01810926) in 5 Italian centres enrolling patients with non-malignant haematological and inherited metabolic disorders transplanted from either a MRD or a MUD, selected using high-resolution typing for HLA-class I/II loci and stringent criteria of HLA-compatibility (>9/10). All patients received the same myeloablative regimen consisting of Treosulfan, Thiotepa and Fludarabine. Enrolled patients were randomized (1:1) to receive either standard or intensified GvHD prophylaxis. Cyclosporine-A plus short-term methotrexate was the standard GvHD prophylaxis in MRD HSCT recipients. In the experimental arm, patients were additionally given ATLG (Grafalon®, Neovii, 5 mg/kg/day on day -4,-3, and -2). In patients transplanted from a MUD, standard GvHD prophylaxis consisted of Cyclosporine-A plus short-term methotrexate and ATLG (10 mg/kg on day -4,-3 and-2). In the experimental arm, patients were additionally given Rituximab 200 mg/sq on day -1 (Mabthera®, Roche). In MRD group randomization was stratified by disease (hemoglobinopathies vs. other conditions) and in the MUD group by center. For patients given MRD HSCT, the primary end-point was the probability of survival (SUR) free from: a) primary and secondary GF, b) grade II-IV aGvHD, c) chronic GvHD (cGvHD), d) death, whichever occurred first. For patients transplanted from a MUD, the primary end-point was the SUR probability free from: a) grade II-IV aGvHD, b) EBV viremia (>1,000 copies of viral DNA/ml whole blood), whichever occurred first. Secondary endpoint was overall SUR (OS). Statistical analyses were conducted according to intention-to-treat. FINDINGS: Between August 2011 and February 2018, 126 patients were enrolled. Patient and disease characteristics by randomized treatment are shown in Table 1. Median age at HSCT was 6.1 years in the MRD group (range 0.8-38) and 4.9 years in the MUD group (range 0.9-20.7). Median follow-up was 3.6 years. Among the 51 MRD-HSCT recipients, 25 were randomly assigned to the ATLG group and 26 to the NO-ATLG group. No death and no cases of grade II-IV aGvHD were observed in either of the two randomization arms. Two GF occurred in each of the two arms, while 1 and 2 cases of cGvHD occurred in the ATLG and NO-ATLG groups, respectively. Consequently, no statistically significant difference in the probability of SUR without events was observed (p=0.75) and the 3-years estimates (±SE) were 86.9%±7.1% vs. 83.8%±7.5%, respectively. In the MUD setting, 38 patients were allocated in the Rituximab group and 37 in the NO-Rituximab group. Although no statistically significant difference in OS (p=0.21) was observed between the two arms (3-years estimates: 94.1%±4.1% for Rituximab, 85.7%±5.9% for No-Rituximab), patients receiving Rituximab had a better probability of SUR without events (73.0%±7.3% vs 26.5%±7.3%, respectively; p=0.0002), entirely due to a lower incidence of EBV viremia. One case of fatal post-transplant lymphoproliferative disorder was observed in the No-Rituximab arm. Eight patients developed grade II-IV aGvHD in each of the two arms. No patient has persistent dependence on ivIG replacement therapy. CONCLUSIONS Our data indicate that, in patients with non-malignant disorders given a MRD HSCT, the addition of ATLG does not confer any advantage in the prevention of both acute and chronic GvHD, as well as of GF. In MUD-HSCT recipients, the administration of a fixed dose of pre-transplant Rituximab as part of the conditioning regimen does not affect the risk of aGvHD and transplant-related mortality, while it significantly reduces the incidence of episodes of EBV-viremia, without impairing B-cell recovery. Disclosures Algeri: Bluebird bio: Consultancy, Honoraria; Miltenyi: Honoraria; Atara Biotherapeutics: Consultancy, Honoraria. Merli:Novartis: Honoraria; Sobi: Consultancy; Amgen: Honoraria; Bellicum: Consultancy. Locatelli:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Miltenyi: Honoraria; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Collection of an adequate amount of autologous haematopoietic stem progenitor cells (HSPC) is required for ex vivo manipulation and successful engraftment for certain inherited disorders. Fifty-seven paediatric patients (age 0.5–11.4 years) underwent a bone marrow harvest for the purpose of HSPC gene therapy (GT), including adenosine deaminase-severe combined immunodeficiency (ADA-SCID), Wiskott–Aldrich syndrome (WAS) and metachromatic leukodystrophy (MLD) patients. Total nucleated cells and the percentage and absolute counts of CD34+ cells were calculated at defined steps of the procedure (harvest, CD34+ cell purification, transduction with the gene transfer vector and infusion of the medicinal product). A minimum CD34+ cell dose for infusion was 2 × 106/kg, with an optimal target at 5–10 × 106/kg. Median volume of bone marrow harvested was 34.2 ml/kg (range 14.2–56.6). The number of CD34+ cells collected correlated inversely with weight and age in all patients and particularly in the MLD children group. All patients reached the minimum target dose for infusion: median dose of CD34+ cells/kg infused was 10.3 × 106/kg (3.7–25.9), with no difference among the three groups. Bone marrow harvest of volumes > 30 ml/kg in infants and children with ADA-SCID, WAS and MLD is well tolerated and allows obtaining an adequate dose of a medicinal product for HSPC-GT.

Hematopoietic stem-cell transplantation (HSCT) is currently the only curative therapeutic option for the treatment of thalassemia. In spite of the high cure rate, HSCT can lead to life-threatening adverse events in some patients. Busulfan (Bu) is a key component of the conditioning regimen prior to HSCT. Inter-individual differences in Bu pharmacokinetics (PK) are hypothesized to influence Bu efficacy and toxicity. Since Bu is mainly metabolized by glutathione S-transferase (GST), we investigated the relationship of GSTA1 and GSTM1 genotypes with first-dose PK and HSCT outcomes in 44 children with thalassemia intermedia and thalassemia major. All children received a myeloablative conditioning regimen with IV Bu. Association analysis revealed a relationship between GSTA169C>T (or haplotype *A/*B) and first Bu dose PK that was dependent on sex and Pesaro risk classification (PRC). Among female patients and patients with PRC I–II, homozygous individuals for the GSTA1T−69 allele defining haplotype *B, had higher Bu exposure and lower clearance (P⩽0.01). Association with HSCT outcomes showed that patients with the GSTM1 null genotypes had higher occurrence of regimen-related toxicity (P=0.01). These results suggest that GST genotypes could be useful to tailor the first Bu dose accordingly to improve HSCT outcome.

In the last decade many studies unraveled the bone marrow (BM) niche regulation and crosstalk with hematopoietic stem cells (HSC) in steady state conditions and malignancies, but HSC-niche interactions are still underexplored in hematological inherited disorders. We have recently provided the first demonstration of impaired HSC function caused by an altered BM niche in a non-malignant disease, beta-thalassemia (BT) (Aprile et al., Blood 2020). BT is a congenital hemoglobin disorder resulting in severe anemia, ineffective erythropoiesis and multi-organ secondary complications, such as bone defects. It is one of the most globally widespread monogenic diseases, which can be cured by transplantation of HSC from compatible healthy donors or autologous HSC from patients upon gene therapy. Cases of graft failure have been reported, but causes have not been deeply investigated and might include an impaired HSC function and a defective supporting activity of the BM niche, worsened by age and disease progression. We showed that the prolonged residence of HSC into an altered BM stromal niche in BT Hbbth3/+ (th3) mice negatively affects stem cell number, quiescence and self-renewal. Moreover, we demonstrated that correction of HSC-stromal niche crosstalk rescues BT HSC function by in vivo reactivation of parathyroid hormone (PTH) signaling. Consistently with the common finding of osteoporosis in BT patients, we found reduced bone deposition and low levels of PTH also in the murine model. We investigated the potential mechanisms underlying the decreased PTH and bone defect and we focused on the role of fibroblast growth factor-23 (FGF-23). FGF-23 is a systemic hormone mainly secreted by osteocytes, which acts as negative regulator of bone metabolism by inhibiting bone mineralization and PTH production by parathyroid glands. Since FGF-23 is positively modulated by the anemia-related factor erythropoietin (EPO), we hypothesized that the high EPO levels in BT, subsequent to ineffective erythropoiesis, might contribute to increase FGF-23. We measured high levels of circulating FGF-23 in th3 mice (wt vs. th3: 399.7±69.77 vs. 1975±209.3 pg/ml, p Our findings uncover an underexplored role of FGF-23 in bone and BM niche defects in BT, as a condition of severe anemia and chronic EPO stimulation. The inhibition of FGF-23 signaling might provide a novel strategy to ameliorate bone compartment and restore HSC-BM niche interactions in BT, with a potential translational relevance in improving HSC transplantation approaches. Disclosures Motta: Sanofi Genzyme: Honoraria. Cappellini:BMS: Honoraria; CRISPR Therapeutics, Novartis, Vifor Pharma: Membership on an entity's Board of Directors or advisory committees; Genzyme/Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Predicting mobilization failure before it starts may enable patient-tailored strategies. Although consensus criteria for predicted PM (pPM) are available, their predictive performance has never been measured on real data. We retrospectively collected and analyzed 1318 mobilization procedures performed for MM and lymphoma patients in the plerixafor era. In our sample, 180/1318 (13.7%) were PM. The score resulting from published pPM criteria had sufficient performance for predicting PM, as measured by AUC (0.67, 95%CI: 0.63–0.72). We developed a new prediction model from multivariate analysis whose score (pPM-score) resulted in better AUC (0.80, 95%CI: 0.76–0.84, p < 0001). pPM-score included as risk factors: increasing age, diagnosis of NHL, positive bone marrow biopsy or cytopenias before mobilization, previous mobilization failure, priming strategy with G-CSF alone, or without upfront plerixafor. A simplified version of pPM-score was categorized using a cut-off to maximize positive likelihood ratio (15.7, 95%CI: 9.9–24.8); specificity was 98% (95%CI: 97–98.7%), sensitivity 31.7% (95%CI: 24.9–39%); positive predictive value in our sample was 71.3% (95%CI: 60–80.8%). Simplified pPM-score can “rule in” patients at very high risk for PM before starting mobilization, allowing changes in clinical management, such as choice of alternative priming strategies, to avoid highly likely mobilization failure.

Introduction. Despite the increasing of number of patients with Sickle Cell Disease (SCD) in Italy, due to multi-ethnic migratory phenomena, a large percentage of Caucasian sickle population is already present in Italy mainly with b-thal/HbS genotype. Red cell transfusion is one effective treatment for both acute and chronic complications of SCD, while hydroxycarbamide (HC) is used to reduce the frequency of painful vaso-occlusive crises (VOCs) and decrease the need for blood transfusion. Through the National Comprehensive Reference Centers for SCD, the Italian Society of Thalassemia and Hemoglobinopathies (SITE), in collaboration with the Society Italian Transfusion Medicine and Immunohematology (SIMTI) and the Italian Association of Hematology and Pediatric Oncology (AIEOP) conducted a national survey to collect information on different therapeutic approaches used for SCD patients. Aim. To assess therapeutic approaches used a large Italian cohort of patients with SCD, accounting for age, genotype and ethnicity. Patients and Methods. Observational Longitudinal Systemic Multicentre Study (https://clinicaltrials.gov/ct2/show/NCT03397017). Data were collected from 2015 to 2018 through a standard web-based application (www.SITE-italia.org) encrypted by the Central Server. All the SCD patients, treated or not treated, were included in order to identify the overall number and all gave written informed consent. The study was approved by Ethics Committee of Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico of Milan, Italy. Results. Thirty-four centers were involved from 14 Italian regions and 1,579 patients were enrolled (802 male and 777 female; median age 23 years - IQR, 25th-75th 10-41 yrs). Genotype, age and ethnicity distribution are shown in Table 1A. As expected, the median age of non-Caucasian patients, mainly HbSS, is significantly lower than Caucasian ones (p Out of 1,579, 365 SCD patients (23%) did not receive any therapy. Acute transfusion regimen (ATR), Chronic transfusion regimen (CTR) and HC were given in monotherapy, respectively in 160, 226 and 197 patients, or in succession/combination in 631 (Table 1B), distributed throughout genotypes. The main reasons for ATR were acute anemia (384 events) and VOCs (352), followed by acute chest syndrome (ACS; 170), surgery (82), pregnancy (64), splenic sequestration (26), stroke (9); multi-organ failure (MOFs 6) and priapism (5). For CRT, it was acute anemia (306 events) and prevention of VOCs (371), ACS (107), primary stroke prevention (78) and secondary prevention stroke (55), pain HC-resistent (39) and leg ulcers (12). For 275 patients out of 631 it was possible to follow the timing of therapy switching (Table 1C). Of 275 patients, 67.6% switched from ATR/CRT to HC, 2.9% from HC to CRT and 6.5% stopped every therapy. Out of 275 patients, 104 were treated with overlapping therapeutic regimen. Discussion. The significant difference of age in Caucasian and non-Caucasian patients is probably due to the efficacy of the national prevention program of hemoglobinopathies, because the non-Caucasian patients are prevalently born out of Italy. The transfusional approach is similar in HbSS and b°-thal/HbS and b+-thal/HbS patients regarding both ATR and CTR. HbSC genotype needed less therapies(p Summary/Conclusion. The transfusional approach is similar in HbSS, b°-thal/HbS and b+-thal/HbS patients with similar indications, prevalently VOCs and anemia. The significant higher age in Caucasian cohort and the consequent long term follow up could be the cause of variable therapeutic approach observed, however Hydroxycarbamide seemed to be the therapy more frequently used and finally suggested to manage chronic manifestations. Figure. Figure. Disclosures Origa: Apopharma: Honoraria; Novartis: Honoraria; Bluebird Bio: Consultancy; Cerus Corporation: Research Funding. Forni:Apopharma: Other: DSM Board; Celgene: Research Funding; Novartis: Other: travel expenses, Research Funding; Shire: Research Funding; Roche: Consultancy.

Patients with inborn error diseases can be candidates for autologous haematopoietic stem cells (HSC) gene therapies (GT) but may require negative viral screening, including Hepatitis C (HCV), to allow HSC manipulation in Good Manufacturing Practices areas. In case of HCV positivity, patients might be excluded from life-saving treatments. As HCV antibodies could be negative in young infant immunodeficient patients due to their immature/impaired immune system, or positive due to maternal-fetal antibody transmission, the risk is usually also evaluated on the basis of the HCV-RNA. This article is protected by copyright. All rights reserved.

BACKGROUND In allogeneic hematopoietic stem cell (HSC) transplantation, the collection of an appropriate number of HSCs while maintaining a high level of safety for healthy donors is fundamental. Inadequate HSC mobilization can be seen with the standard use of granulocyte–colony-stimulating (G-CSF). Plerixafor (PL) is a chemokine receptor CXC Type 4–stromal-derived factor 1 inhibitor; its HSC-mobilizing properties are synergistic with G-CSF in poor mobilizing patients. The use of PL as adjuvant or alternative to G-CSF in healthy donors has shown a good safety profile but is so far off-label. STUDY DESIGN AND METHODS We report 10 healthy HSC donors treated with PL because of insufficient response to G-CSF alone or contraindication to G-CSF. Eight donors did not mobilize enough CD34+ cells with G-CSF alone because poor mobilizers or because insufficient HSCs were harvested according to the clinical need of the patient; in two cases G-CSF administration and marrow harvest were unfeasible or contraindicated in the donor. RESULTS The use of PL for mobilization increased the number of circulating CD34+ cells by 2.8-fold and the CD34+/kg collection by 3.0-fold. Only mild adverse events were reported (bone pain or discomfort) and not univocally attributable to PL. Rate of engraftment and graft-versus-host disease were similar to those seen in recipients of grafts from G-CSF only–mobilized donors. CONCLUSION We exposed 10 allogeneic donors to mobilization with PL. PL was well tolerated in all cases and ensured procurement of an adequate graft for transplantation resulting in a normal hematopoietic engraftment.

Allogeneic transplantation is the only potentially curative strategy for myelofibrosis, even in the era of new drugs that so far only mitigate symptoms. The choice to proceed to allogeneic transplantation is based on several variables including age, disease phase, degree of splenomegaly, donor availability, comorbidities and iron overload. These factors, along with conditioning regimen and time to transplantation, may influence the outcome of ASCT. We report 14 patients affected by myelofibrosis with a median age of 57 years (range, 41–76) receiving a treosulfan-fludarabine based reduced toxicity conditioning. Patients (pts) received a stem cell transplantation from an HLA identical (n = 10) or matched unrelated donor (n = 4). All pts had a complete myeloablation followed by engraftment and in 12 out of 13 evaluated pts donor chimerism was 100% at 1 month. In most cases a reduction of splenomegaly and a reduction (or resolution) of bone marrow fibrosis was observed. After a median follow-up of 39 months (range, 3–106), the 3-year probability of overall survival and disease free survival was 54 +/− 14% and 46 +/− 14%, respectively. The cumulative incidence of non-relapse mortality at 2 years was 39 +/− 15%. Causes of non-relapse mortality were: infection (n = 2), GvHD (n = 2) and haemorrhage (n = 1). We can conclude that a treosulfan and fludarabine based conditioning has a potent myeloablative and anti-disease activity although non-relapse mortality remains high in this challenging clinical setting. Copyright © 2014 John Wiley & Sons, Ltd.

Background Infections and graft-vs-host disease (GvHD) still represent major, not easily predictable complications in allogeneic hematopoietic stem cell transplant (allo-HSCT). Both conditions have been correlated to altered enteric microbiome profiles during the peritransplant period. The main objective of this study was to identify possible early microbiome-based markers useful in pretransplant risk stratification. Methods Stool samples were collected from 96 consecutive patients at the beginning of the pretransplant conditioning regimen (T0) and at 10 (T1) and 30 (T2) days following transplant. When significant in univariate analysis, the identified microbiome markers were used in multivariate regression analyses, together with other significant clinical variables for allo-HSCT-related risk stratification. Four main outcomes were addressed: (1) septic complications, (2) GvHD, (3) relapse of the underlying disease, and (4) mortality. Results The presence of >5% proinflammatory Enterobacteriaceae at T0 was the only significant marker for the risk of microbiologically confirmed sepsis. Moreover, ≤10% Lachnospiraceae at T0 was the only significant factor for increased risk of overall mortality, including death from both infectious and noninfectious causes. Finally, a low bacterial alpha-diversity (Shannon index ≤ 1.3) at T1 was the only variable significantly correlating with an increased risk of GvHD within 30 days. Conclusions Microbiome markers can be useful in the very early identification of patients at risk for major transplant-related complications, offering new tools for individualized preemptive or therapeutic strategies to improve allo-HSCT outcomes.

For decades, bone marrow (BM) has been the preferred source of hematopoietic stem and progenitor cells (HSPCs) for transplants following myeloablative conditioning. At present, mobilized peripheral blood stem cells are commonly used for transplantation, particularly in the autologous setting.[1][1

The management of Hodgkin's lymphoma (HL) recurring after allogeneic stem cell transplantation is challenging. We retrospectively describe 18 adults treated with bendamustine followed by escalated donor lymphocyte infusion. Hematological toxicity was manageable (39% grade III to IV neutropenia and 28% grade III to IV thrombocytopenia). The overall response rate was 55%, with 3 complete and 7 partial responses. Median overall and progression-free survival were 11 (range, 1 to 52) and 6 (range, 1 to 28) months, respectively. One-year overall survival of responders (complete or partial) was 70% (95% confidence interval, 42% to 98%), although it was only 16% for nonresponders (n = 8). Our data show that bendamustine followed by donor lymphocyte infusion is feasible and can be efficacious as salvage treatment in HL relapsing after an allograft. (C) 2014 American Society for Blood and Marrow Transplantation.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only cure for several patients with high-risk hematological malignancies. Recent advances in supportive therapies have significantly reduced the treatment-related mortality over the last decades. Nevertheless graft-versus-host disease (GvHD) still represents a major complication, and research is needed to achieve further progress in this area of transplantation. Moreover, although initial studies suggested relative equivalence, recent and large prospective studies showed higher rates of acute and chronic GvHD, and worse survival in allo-HSCT from unrelated donors (URD) compared with HLA-identical sibling donors. Following our encouraging results in haplodentical setting with the more recently post-transplantation cyclophosphamide (PTCy) and sirolimus as GvHD prophylaxis (Cieri et al, 2015), in this study we investigated whether the incorporation of low dose anti-thymocyte globulin (ATG) to PTCy and sirolimus GvHD prophylactic approach, may alleviate some of the increased alloreactivity associated with URD transplants. We retrospectively evaluated a cohort of 21 haematological patients receiving URD allo-HSCT in the San Raffaele Haematology and BMT Unit, from 2013 to 2015. All subjects had high-risk hematologic malignancies, with the most common diagnosis being myeloid diseases (52%). A total of 11 patients had active disease at HSCT, while 9 were in hematologic remission. Nine patients scored high according to disease risk index defined by Armand et al, 10 scored intermediate, while only 2 had a low disease score. Myeloablative conditioning consisted of treosulfan (14 g/m2/day) on days -6 to -4, fludarabine (30 mg/m2/day) on days -6 to -2, and melphalan (70 mg/m2/day) on days -2 and -1, followed by T-replete G-CSF-mobilized PBSCs (n=19) or BM grafts (n=2). Whether 12 patients received stem cells from HLA- matched URD (fully 10/10 HLA matched), the remaining 9 had one-locus HLA-mismatched from their donors. During conditioning patients received ATG-Fresenius 5 mg/kg per day IV on day -4 to -2. In vivo B-cell depletion was obtained by rituximab (i.v. 375mg/m2 given as a single dose on day -1). Postgrafting immunosuppression consisted of PTCy (50 mg/kg/day) on days 3 and 4. Sirolimus was given orally from day 5, and monitored to maintain a target therapeutic plasma level of 5-14 ng/ml. According to chimeric status and evidence of GVHD, the dosage of sirolimus was tapered during the second month post-transplantation, ending in complete withdrawal within the sixth month after HSCT. Mycophenolate mofetil (MMF) was initiated orally at 10 mg/kg t.i.d. on day 5 after HSCT, and withdrawn on day 30. Median follow up was 247 days (range 29-486) from HSCT. All patients were engrafted in a median time of 17 days (range, 14-51 days), with full donor chimerism achieved by day 30. Poor graft function was observed in 11 patients. Post-HSCT recovery of lymphocyte subsets was lengthy as compared to other unmanipulated HSCT, with a median time to CD3>100/ml of 41 days (range, 22-389 days) by flow-cytometry, while 5 patients never reached immune reconstitution. All except one developed febrile neutropenia during aplasia. We observed a high rate of serious infections: severe pneumonia in 7 cases (5 required NIV, 4 were admitted to ICU), CMV reactivation in 13 (3 CMV disease), HHV6 reactivation in 10, BK virus haemorrhagic cystitis in 2 patients. Although the overall mortality associated with these complications was limited, as evidenced by a favourable NRM, it caused significant morbidity in patients and often required aggressive therapies, potentially contributing to poor graft function. The incidences of acute and chronic GVHD were low. A grade II-IV acute GvHD was reported in 10% patients, while five patients developed chronic GvHD (mild in 4 cases, only one moderate). Non-relapse mortality (NRM) at 100 days and 1 year was 4.8% and 20.7%, respectively. The estimated 1-year overall survival (OS) and relapse incidence were 51% and 22.5% respectively. Although limited by a small number of patients with relatively short follow-up, our study suggests that URD allo-HSCT with ATG, PTCy and sirolimus-based GvHD prophylaxis, can be very effective in preventing GvHD, but at the expense of delayed immune reconstitution and high rate of infectious complications, while warranting acceptable NRM and relapse incidence. Disclosures Bonini: MolMed S.p.A: Consultancy.

Coadministration of posaconazole and sirolimus in allogeneic hematopoietic stem cell transplant recipients

Detection of hemoglobin (Hb) variants represents an important issue for diagnosis and adequate treatment of hemoglobinopathies. The Capillarys 2 Flex Piercing analyzer (Capillarys) by Sebia is routinely used in our clinical laboratories to detect Hb variants in peripheral blood (PB). This automated method separates Hb fractions by capillary electrophoresis, giving a spectrophotometric measure of their relative proportion. The scientific research in the field of hemoglobinopathies needs robust procedures to evaluate the efficacy of experimental therapies, as gene therapy. We investigated for the first time the feasibility to use Capillarys on cellular lysates from in vitro erythroid cultures. Because total Hb concentration in erythroid lysates is up to 20-fold lower than in hemolysates from PB, we analyzed diluted blood samples, thanks to the manual mode included in the Capillarys setting. We compared analytical precision, accuracy, sensitivity, and specificity of this procedure to the automatic method, routinely used in diagnostics. For instance, adult Hb intra- and interassay precision were estimated as coefficient of variation 0.2% and 0.3%, respectively. The manual mode is less robust for detection of fractions

Polymorphisms in the 3' untranslated region (3'UTR) of HLA-G, an important player in immunological tolerance, could be involved in post-transcriptional expression control, and their association with different clinical immune-related conditions including autoimmunity and transplantation is of mounting interest. Most studies have focused on a 14 base pair (bp) insertion/deletion (ins/del), while additional single-nucleotide polymorphisms (SNPs) in the HLA-G 3'UTR have been described but not extensively investigated for their clinical relevance. Here we have comparatively studied the association between 3'UTR haplotypes of HLA-G, or the 14 bp ins/del, with clinical outcome of HLA-identical sibling hematopoietic stem cell transplantation (HSCT) in 147 Middle Eastern beta-thalassemia patients. Sequence based typing of 3'UTR HLA-G polymorphisms in the patients and in 102 healthy Italian blood donors showed strong linkage disequilibrium between the 14 bp ins/del and five 3'UTR SNPs, which together could be arranged into eight distinct haplotypes based on expectation-maximization studies, with four predominant haplotypes (UTRs1-4). After HSCT, we found a moderate though not significant association between the presence of UTR-2 in double dose and protection from acute graft versus host disease (hazard ratio (HR) 0.45, 95% confidence intervals (CI): 0.14-1.45; P = 0.18), an effect that was also seen when the corresponding 14 bp ins/ins genotype was considered alone (HR 0.42, 95% CI: 0.16-1.06; P = 0.07). No association was found with rejection or survival. Taken together, our data show that there is no apparent added value of considering entire 3'UTR HLA-G haplotypes for risk prediction after allogeneic HSCT for beta-thalassemia.

Introduction Allogeneic stem cell transplantation (HCT) survivors are at a relevant risk of developing long-term complications such as chronic GvHD (cGvHD), which importantly affects their quality of life and increases their morbidity and mortality. Being able to early identify high risk patients would enable us to tailor preventive strategies. Current approach on prophylaxis of GvHD is lacking of predictive biomarkers that could guide patient-tailoring of drugs choice, tapering and treatment schedules. Immune system is the cause of cGvHD but is also a target of it, and cGvHD patients are characterized by lymphoid hypocellularity. Moreover, immune reconstitution (IR) is a good candidate biomarker being it an easily-available and reproducible parameter. We investigated IR variables as predictive biomarker of cGvHD. Methods A standardized follow-up of HCT-survivors is applied at our center. We analyzed 307 adult patients consecutively undergoing first allogeneic HCT transplant between July 2012 and December 2016 at our Institution. A written consent was given for the use of medical records for research in accordance with the Declaration of Helsinki. Median follow-up for surviving patients was 2.8 years (range 1.1-5.5). We prospectively collected IR data of our entire cohort at specific time-points (+30, +60, +90, +180, +365 days) and followed patients up recording events. IR variables were CD3+, CD3+CD4+, CD3+CD8+, CD19+, CD56+ cell counts, measured by flow-citometry, and immunoglobulins IgG, IgA and IgM levels, measured by immunoturbidimetric assays. Time as a continuous parameter could not be studied since the number of events would have been too low for the analysis. For this reason, a series of landmark analyses were performed at 3, 6 and 12 months post-HCT in order to identify predictive factors of cGvHD, transplant-related mortality (TRM), progression-free survival (PFS) and overall survival (OS) for patients alive and in good conditions at the beginning of each time interval. Factors predicting cGvHD incidence and survival endpoints were studied using multivariate analysis by Cox regression model. Variables included in the model were patient and donor age and Sorror-Comorbidity Index (according to median values), disease-related index, type of donor, stem cell source, IR values at the timepoint according to landmark cut-off for cell counts and median values for immunoglobulin levels. A backward stepwise procedure was used for variable selection with a p-value Results Chronic-GvHD of any grade and severity was diagnosed in 111 patients. Immune recovery in our cohort was in line with the current knowledge: CD3+CD8+ and NK (CD56+) cells normalized first, followed by CD3+ and CD3+CD4+ cell. B cells (CD19+) took at least 1 year to normalize in terms of absolute counts. IgM levels were the first to rise among immunoglobulins, followed by IgG and then IgA which can also be subnormal for a long time after transplant. Results of multivariate analysis are shown in Table 1. Single lymphocyte subset counts did not prove to be associated to cGvHD onset significantly; conversely, immunoglobulins were strongly predictive of cGvHD in our multivariate model. Median time to GvHD onset was 198 days, thus the most important analysis was the one performed at +90 days as the majority of patients had still not developed cGvHD. IgG, IgA and IgM at +90 days from HCT below the median value were found before the onset of GvHD and could predict its onset. This data were confirmed on the analysis at later time-points in which low IgG levels predicted cGvHD diagnosis. Conclusions Day-90 low immunoglobulin levels predict cGvHD, confirming that subclinical immune dysregulation mechanisms could be already present before overt clinical onset of cGvHD symptoms. Early prediction of subsequent cGvHD will be operationally translated into patient-tailored preventive measures. Disclosures Bonini: Intellia Therapeutics: Research Funding.

Despite advances in graft-versus-host-disease (GVHD) treatment, it is estimated that overall survival (OS) at 2 years for hematopoietic cell transplantation (HCT) recipients who experience steroid-resistant GVHD is 10%. Among recent therapeutic approaches for GVHD treatment, mesenchymal stromal cells (MSCs) hold a key position. We describe a multicenter experience of 11 pediatric patients diagnosed with acute or chronic GVHD (aGVHD, cGVHD) treated for compassionate use with GMP-grade unrelated HLA-disparate donors' bone marrow-derived MSCs, expanded in platelet-lysate (PL)-containing medium. Eleven patients (aged 4-15 years) received intravenous (i.v.) MSCs for aGVHD or cGVHD, which was resistant to multiple lines of immunosuppression. The median dose was 1.2 x 10(6)/kg (range: 0.7-3.7 x 10(6)/kg). No acute side effects were observed, and no late side effects were reported at a median follow-up of 8 months (range: 4-18 months). Overall response was obtained in 71.4% of patients, with complete response in 23.8% of cases. None of our patients presented GVHD progression upon MSC administration, but 4 patients presented GVHD recurrence 2 to 5 months after infusion. Two patients developed chronic limited GVHD. This study underlines the safety of PL-expanded MSC use in children. MSC efficacy seems to be greater in aGVHD than in cGVHD, even after failure of multiple lines of immunosuppression.

Bone marrow (BM) contains a population of mesenchymal stromal cells (MSC) that, together with endothelial cells and osteoblasts, provide a specific microenvironment to support hematopoietic stem cell homeostasis. Beta-thalassemia (BT) is an hereditary blood disorder characterized by reduced or absent synthesis of hemoglobin beta-chains. Data on the mesenchymal compartment in BT patients are scarce. We isolated and characterized MSCs from BT and healthy donor (HD) BM samples. BT-MSCs showed a reduced clonogenic capacity, delay in colony formation, lower numbers of CFU-Fs and longer population doubling time. Similarly, we observed an altered differentiation capacity into adipocytes and osteoblasts. Both HD- and BT-MSCs express the canonical mesenchymal markers. On the contrary, the expression of CD146 and CD271 was extremely reduced in BT-MSCs, indicating a pauperization of the most primitive stem cell pool. We analyzed the expression of genes involved in the crosstalk between MSCs and HSCs and found a reduced expression of Cxcl12, SCF and Angp1 in BT-MSCs. Several genes relevant for MSC functionality were also downregulated in BT-MSCs. We demonstrated that MSCs are able to uptake and store iron. ROS levels were increased in BT-MSCs possibly due to altered anti-oxidant response and iron overload associated with blood transfusions. Importantly, higher level of ROS and reduced expression of primitive markers were observed in HD-MSCs cultured in presence of iron, underlying the importance of iron level for normal MSC function. In conclusion, we showed an impairment in the mesenchymal niche of BT-BM possibly associated with prolonged iron exposure. Disclosures Marktel: GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding. Ciceri: GSK: Other: B-thalassemia gene therapy was developed by Fondazione Telethon and Ospedale San Raffaele and has been inlicenced by GSK that provides funding for the clinical trial, Research Funding.

The extensive exploitation of the antitumor effect of donor lymphocytes infused after allogeneic hematopoietic stem-cell transplantation (allo-HSCT) is limited by the risk of graft-versus-host disease (GvHD). To overcome this limitation, we investigated the therapeutic potential of donor lymphocytes engineered with the suicide gene thymidine kinase of herpes simplex virus (TK) in 23 patients experiencing recurrence of hematologic malignancies after allo-HSCT. Long-term follow-up of infused patients included analysis of engraftment of genetically engineered lymphocytes, in vivo assessment of antitumor effect, and control of GvHD by ganciclovir. All 17 patients evaluable for engraftment and graft-versus-leukemia (GvL) had circulating TK+ cells detectable beginning at a median time of 18 days. Eleven patients (65%) experienced a substantial clinical benefit resulting in 6 (35%) complete remissions and 5 (29%) partial responses. The antitumor effect tightly correlated with the in vivo received ganciclovir, resulting in elimination of TK+ cells and effective and selective treatment of GvHD. Immunization against HSV-TK was observed in 7 patients but did not preclude an effective GvL. These data validate the feasibility, safety, and efficacy of TK+ cells in the context of allografting and represent the basis for a broader application of this technology. The extensive exploitation of the antitumor effect of donor lymphocytes infused after allogeneic hematopoietic stem-cell transplantation (allo-HSCT) is limited by the risk of graft-versus-host disease (GvHD). To overcome this limitation, we investigated the therapeutic potential of donor lymphocytes engineered with the suicide gene thymidine kinase of herpes simplex virus (TK) in 23 patients experiencing recurrence of hematologic malignancies after allo-HSCT. Long-term follow-up of infused patients included analysis of engraftment of genetically engineered lymphocytes, in vivo assessment of antitumor effect, and control of GvHD by ganciclovir. All 17 patients evaluable for engraftment and graft-versus-leukemia (GvL) had circulating TK+ cells detectable beginning at a median time of 18 days. Eleven patients (65%) experienced a substantial clinical benefit resulting in 6 (35%) complete remissions and 5 (29%) partial responses. The antitumor effect tightly correlated with the in vivo received ganciclovir, resulting in elimination of TK+ cells and effective and selective treatment of GvHD. Immunization against HSV-TK was observed in 7 patients but did not preclude an effective GvL. These data validate the feasibility, safety, and efficacy of TK+ cells in the context of allografting and represent the basis for a broader application of this technology.

Donor lymphocyte infusions (DLI) are an effective treatment for patients with chronic myeloid leukemia (CML) in relapse after allografting but the optimal cell dose has yet to be identified. To address this question, we investigated the factors affecting the dose required to achieve remission (effective cell dose, (ECD)) in 81 patients treated with an escalating dose regimen. The overall proportion of patients who achieved a molecular remission was 88%. The cumulative proportion of remitters increased significantly at each dose level. With a CD3(+) cell doseor =10(7)/kg, 56% of patients in molecular/cytogenetic relapse obtained molecular remission, whereas only 20% of those in hematologic relapse did so. At the same cell dose, 58% of patients who received lymphocytes from volunteer unrelated donors achieved remission, as compared to 29% of those who received DLI from sibling donors. We conclude that the response to DLI is dose-dependent and that the ECD is influenced by the quantity and phase of CML at relapse and degree of donor/recipient histocompatibility.

Haploidentical hematopoietic stem cell transplantation (HSCT) performed using bone marrow (BM) grafts and post-transplantation cyclophosphamide (PTCy) has gained much interest for the excellent toxicity profile after both reduced-intensity and myeloablative conditioning. We investigated, in a cohort of 40 high-risk hematological patients, the feasibility of peripheral blood stem cells grafts after a treosulfan-melphalan myeloablative conditioning, followed by a PTCy and sirolimus-based graft-versus-host disease (GVHD) prophylaxis (Sir-PTCy). Donor engraftment occurred in all patients, with full donor chimerism achieved by day 30. Post-HSCT recovery of lymphocyte subsets was broad and fast, with a median time to CD4 > 200/mu L of 41 days. Cumulative incidences of grade II to IV and III-IV acute GVHD were 15% and 7.5%, respectively, and were associated with a significant early increase in circulating regulatory T cells at day 15 after HSCT, with values < 5% being predictive of subsequent GVHD occurrence. The 1-year cumulative incidence of chronic GVHD was 20%. Nonrelapse mortality (NRM) at 100 days and 1 year were 12% and 17%, respectively. With a median follow-up for living patients of 15 months, the estimated 1-year overall and disease-free survival (DFS) was 56% and 48%, respectively. Outcomes were more favorable in patients who underwent transplantation in complete remission (1-year DFS 71%) versus patients who underwent transplantation with active disease (DFS, 34%; P = .01). Overall, myeloablative haploidentical HSCT with peripheral blood stem cells (PBSC) and Sir-PTCy is a feasible treatment option: the low rates of GVHD and NRM as well as the favorable immune reconstitution profile pave the way for a prospective comparative trial comparing BM and PBSC in this specific transplantation setting. (C) 2015 American Society for Blood and Marrow Transplantation.

Hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA) haploidentical family donors is a promising therapeutic option for high-risk hematologic malignancies. Here we explored in 121 patients, mostly with advanced stage diseases, a sirolimus-based, calcineurin-inhibitor-free prophylaxis of graft-versus-host disease (GvHD) to allow the infusion of unmanipulated peripheral blood stem cell (PBSC) grafts from partially HLA-matched family donors (TrRaMM study, Eudract 2007-5477-54). Conditioning regimen was based on treosulfan and fludarabine, and GvHD prophylaxis on antithymocyte globulin Fresenius (ATG-F), rituximab and oral administration of sirolimus and mycophenolate. Neutrophil and platelet engraftment occurred in median at 17 and 19 days after HSCT, respectively, and full donor chimerism was documented in patients' bone marrow since the first post-transplant evaluation. T-cell immune reconstitution was rapid, and high frequencies of circulating functional T-regulatory cells (Treg) were documented during sirolimus prophylaxis. Incidence of acute GvHD grade II-IV was 35%, and occurrence and severity correlated negatively with Treg frequency. Chronic GvHD incidence was 47%. At 3 years after HSCT, transpant-related mortality was 31%, relapse incidence 48% and overall survival 25%. In conclusion, GvHD prophylaxis with sirolimus-mycophenolate-ATG-F-rituximab promotes a rapid immune reconstitution skewed toward Tregs, allowing the infusion of unmanipulated haploidentical PBSC grafts. Hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA) haploidentical family donors is a promising therapeutic option for high-risk hematologic malignancies. Here we explored in 121 patients, mostly with advanced stage diseases, a sirolimus-based, calcineurin-inhibitor-free prophylaxis of graft-versus-host disease (GvHD) to allow the infusion of unmanipulated peripheral blood stem cell (PBSC) grafts from partially HLA-matched family donors (TrRaMM study, Eudract 2007-5477-54). Conditioning regimen was based on treosulfan and fludarabine, and GvHD prophylaxis on antithymocyte globulin Fresenius (ATG-F), rituximab and oral administration of sirolimus and mycophenolate. Neutrophil and platelet engraftment occurred in median at 17 and 19 days after HSCT, respectively, and full donor chimerism was documented in patients’ bone marrow since the first post-transplant evaluation. T-cell immune reconstitution was rapid, and high frequencies of circulating functional T-regulatory cells (Treg) were documented during sirolimus prophylaxis. Incidence of acute GvHD grade II–IV was 35%, and occurrence and severity correlated negatively with Treg frequency. Chronic GvHD incidence was 47%. At 3 years after HSCT, transplant-related mortality was 31%, relapse incidence 48% and overall survival 25%. In conclusion, GvHD prophylaxis with sirolimus– mycophenolate–ATG-F–rituximab promotes a rapid immune reconstitution skewed toward Tregs, allowing the infusion of unmanipulated haploidentical PBSC grafts.

Memory stem T cells (TSCM) have been proposed as key determinants of immunologic memory. However, their exact contribution to a mounting immune response, as well as the mechanisms and timing of their in vivo generation, are poorly understood. We longitudinally tracked TSCM dynamics in patients undergoing haploidentical hematopoietic stem cell transplantation (HSCT), thereby providing novel hints on the contribution of this subset to posttransplant immune reconstitution in humans. We found that donor-derived TSCM are highly enriched early after HSCT. We showed at the antigen-specific and clonal level that TSCM lymphocytes can differentiate directly from naive precursors infused within the graft and that the extent of TSCM generation might correlate with interleukin 7 serum levels. In vivo fate mapping through T-cell receptor sequencing allowed defining the in vivo differentiation landscapes of human naive T cells, supporting the notion that progenies of single naive cells embrace disparate fates in vivo and highlighting TSCM as relevant novel players in the diversification of immunological memory after allogeneic HSCT. Memory stem T cells (TSCM) have been proposed as key determinants of immunologic memory. However, their exact contribution to a mounting immune response, as well as the mechanisms and timing of their in vivo generation, are poorly understood. We longitudinally tracked TSCM dynamics in patients undergoing haploidentical hematopoietic stem cell transplantation (HSCT), thereby providing novel hints on the contribution of this subset to post transplant immune reconstitution in humans. We found that donor-derived TSCM are highly enriched early after HSCT. We showed at the antigen specific and clonal level that TSCM lymphocytes can differentiate directly from naïve precursors infused within the graft and that the extent of TSCM generation might correlate with interleukin 7 serum levels. In vivo fate mapping through T-cell receptor sequencing allowed defining the in vivo differentiation landscapes of human naïve T cells, supporting the notion that progenies of single naive cells embrace disparate fates in vivo and highlighting TSCM as relevant novel players in the diversification of immunological memory after allogeneic HSCT.

Stem cell therapy is a promising approach to regenerate healthy tissues starting from a limited amount of self-renewing cells. Immunological rejection of cell therapy products might represent a major limitation. In this study, we investigated the immunological functional profile of mesoangioblasts, vessel-associated myogenic stem cells, currently tested in a phase 1-2a trial, active in our Institute, for the treatment of Duchenne muscular dystrophy. We report that in resting conditions, human mesoangioblasts are poorly immunogenic, inefficient in promoting the expansion of alloreactive T cells and intrinsically resistant to T-cell killing. However, upon exposure to interferon-gamma or differentiation into myotubes, mesoangioblasts acquire the ability to promote the expansion of alloreactive T cells and acquire sensitivity to T-cell killing. Resistance of mesoangioblasts to T-cell killing is largely due to the expression of the intracellular serine protease inhibitor-9 and represents a relevant mechanism of stem cell immune evasion. Stem cell therapy is a promising approach to regenerate healthy tissues starting from a limited amount of self-renewing cells. Immunological rejection of cell therapy products might represent a major limitation. In this study, we investigated the immunological functional profile of mesoangioblasts, vessel-associated myogenic stem cells, currently tested in a phase 1-2a trial, active in our Institute, for the treatment of Duchenne muscular dystrophy. We report that in resting conditions, human mesoangioblasts are poorly immunogenic, inefficient in promoting the expansion of alloreactive T cells and intrinsically resistant to T-cell killing. However, upon exposure to interferon-γ or differentiation into myotubes, mesoangioblasts acquire the ability to promote the expansion of alloreactive T cells and acquire sensitivity to T-cell killing. Resistance of mesoangioblasts to T-cell killing is largely due to the expression of the intracellular serine protease inhibitor-9 and represents a relevant mechanism of stem cell immune evasion.

Graft-versus-host disease (GVHD) is a major complication of allogeneic bone marrow transplantation. One strategy to treat GVHD is to equip donor T cells with a conditional suicide mechanism that can be triggered when GVHD occurs. The herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir system used clinically has several limitations, Including immunogenicity and cell cycle dependence. An alternative switch based on chemically inducible apoptosis was designed and evaluated, A chimeric human protein was expressed comprising an extracellular marker (Delta LNGFR), the Pas intracellular domain, and 2 copies of an FK506-binding protein (FKBP), Primary human T lymphocytes retrovirally transduced with this construct could be purified to homogeneity using immunomagnetic beads. Genetic integrity of the construct was ensured by redesigning repetitive sequences. Transduced T cells behaved indistinguishably from untransduced cells, retaining the ability to mount a specific; antiallogeneic immune response, However, they rapidly underwent apoptosis with the addition of subnanomolar concentrations of AP1903, a bivalent "dimerizer" drug that binds FKBP and induces Pas cross-linking, A single P-hour treatment eliminated approximately 80% of T cells, and multiple exposures induced further apoptosis. T cells were eliminated regardless of their proliferation state, suggesting that the AP1903/Fas system, which contains only human components, is a promising alternative to HSV-fk for treating GVHD, (Blood, 2001; 97:1249-1257) (C) 2001 by The American Society of Hematology.

Background: Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for many haematological diseases. Despite advances in supportive therapies, acute Graft-versus-Host Disease (aGvHD) remains the leading cause of early morbidity and mortality. There are shortcomings in the prediction of aGVHD, indicating the urgent need for non-invasive and reliable laboratory tests to allow a precision-medicine tailored prophylactic approach. Aims: We conducted a prospective observational study to ascertain the potential usefulness of the levels of eleven biomarkers, measured pre- and at +7 days post-alloHSCT, in predicting the development and severity of aGvHD in allo-HSCT patients. These time-points were chosen as early risk stratification may provide a window for additional prophylactic measures. Methods: We collected data from 120 consecutive patients (41 female and 79 male; median age 52, range 19-77 years) who underwent allo-HSCT at our institute between 2014 and 2015. Most patients were affected by myeloid malignancies (AML=52%, MDS=11%, MPN=5%) while 32% were of lymphoid origin (ALL, MM and lymphomas). Revised disease-risk index (DRI, Armand et al.) was low or intermediate for 41% of pts, high for 44% and very high for 15% of them. Most patients (n=101) received peripheral blood stem cells (PBSC). Stem cell donors were unrelated (n=39, HLA matching 9/10 in 14 and 10/10 in 25), family haploidentical (n=56), HLA-identical sibling (n=21), or cord blood (n=4). Post-transplant GvHD prophylaxis was PT-Cy-bases in 65 patients, ATG-bases in 28 patients, both agents in 18 cases whilst 9 patients received neither. Additionally, sirolimus and MMF were used as additional GvHD prophylaxis according to institutional guidelines. The following biomarkers were measured 7 days pre- and post-transplant: interleukin-6 (IL6), Ceruloplasmin(CER), Cholinesterase (CHE), Albumin, Immunoglobulin A, Gammaglutamyl-transferase (GGT), White Blood Cells, Neutrophils, Haemoglobin,Platelets and Glycaemia. ROC curves were used to define optimal cut-offs of the biochemical variables to predict 100-day severe aGvHD and 100-days TRM by logistic regression. Then cumulative incidences curves (CI) for aGvHD and TRM and overall-survival (OS) curves were computed comparing patients under and over the identified cut offs for the variables with the best reported sensitivity and specificity. Multivariate Cox proportional hazard regression was finally applied. Results: The 100-days CI of grade III-IV aGvHD was 13.5%, with a 100-days CI of TRM of 12%. The 1-year OS was 64%. Death was reported in 49 of the total 120 patients: 5/49 deaths were attributable to aGvHD. At baseline, IL6 threshold value of 2.5 pg/ml was significantly associated with the prediction of 100-days severe aGVHD (sens 65%, spec 61%) and TRM (sens 75%, spec 61%). Patients with IL-6 concentration equal or superior to 2.5 pg/ml had higher 100-days CI of severe aGvHD (16% Vs 6%, p 0,03) and TRM (12% Vs 3%, p 0,06). Interestingly, higher IL6 concentrations were associated to worse 1-year OS (42% Vs 82%, p= 129 U/l levels had higher 100-days CI of severe aGVHD (15% vs 7%, p 0,16) and TRM (13% vs 4%, p 0,01), in addition to worse OS (53% vs 71% at 1y, p 0,03). By multivariate analysis (adjusting for age, DRI, Sorror comorbidity index, type of donor, source of stem cells, and backbone of GvHD prophylaxis) pre-transplant IL6 concentrations were significantly associated to severe aGvHD (HR 3, p 0.04), TRM (HR 3, p 0.06), and OS (HR 2.6, p 0,004). Conclusion: In our series, baseline IL6 levels are predictors of aGvHD, especially with regards to grade III/IV aGvHD and translate in a higher risk of TRM and worse OS. This biomarker could be incorporated in a treatment algorithm to increase primary GvHD prophylaxis in patients at risk of severe aGVHD, potentially improving the final outcome of allo-HSCT. Disclosures Ciceri: MolMed SpA: Consultancy.

BACKGROUND: Allogeneic HSCT (allo-HSCT) is the only cure for several patients with hematological malignancies. Recent advances in therapies have significantly reduced transplant-related mortality (TRM); nevertheless infections and graft-versus-host disease (GvHD) still represent major complications. Recent studies indicate that patients undergo dramatic alterations of intestinal microbiota during allo-HSCT, potentially affecting the outcome. An alarming emergence of gram-negative multi-drug-resistant (GN-MDR) pathogens has been increasingly reported from various cancer centers, and the primary site of colonization is mainly the gut. Moreover, GvHD was associated with major shifts in the composition of intestinal microbiota, able to modulate the severity of intestinal inflammation. METHODS: Between October 2014 and March 2016, we have conducted a prospective observational study to examine the intestinal microbiota by NGS techniques in 100 consecutive adult patients, who received allo-HSCT for high-risk hematological malignancies (63.5% acute leukemia). Stem cell donors were family haploidentical (n=45), HLA identical sibling (n=15), unrelated volunteer (n=35), cord blood (n=5). Stem cell source was mainly T-cell replete PBSCs. Fecal specimens have been collected before conditioning (T0), during aplasia (T10) and after engraftment (T30). The fecal microbiome have been analyzed using the 454 GS Junior System, and QIIME software. We defined a threshold of normality for the main phyla on the basis of the control. RESULTS: We observed an important difference in relative percentages of phyla populating the gut between our pts and control. Our patients showed a progressive reduction of the intestinal microbial diversity (alpha diversity) during the transplant process, with a specific decrease of anaerobic species belonging to both Bacteroidetes and Firmicutes phyla, and a relative increase of facultative anaerobic gram-positive families such as Enterococcaceae and Staphylococcaceae. A great variation was observed, particularly between T0 and T30, where we found a significant decrease in alpha diversity (p < 0.001). A significantly different distribution in the baseline microbiome was reported in patients who will experience different clinical outcomes. Patients (n=23) who developed a microbiologically-confirmed sepsis show an increase of Proteobacteria phylum (cut-off 5%; p We identified by multivariate analysis some associations between the relative increase of a specific phylum and clinical variables at baseline. Previous allo-HSCT and prior infections represented strong risk factors for developing colonization by Proteobacteria (exceeding 5%). Sepsis by GN-MDR bacteria was associated to increase in Enterobacteriaceae(exceeding 5%; p 0.011). Interestingly, significant microbioma changes were observed at 10 days after transplant, in patients who developed a subsequent acute GvHD, with a predominant role played by gram-positive bacteria belonging to Firmicutes. More in details, the presence of Lachnospiraceae was associated to a decreased risk of developing acute GvHD (p=0.04 and RR= 4.35), whereas dominance of Enterococcaceae (p CONCLUSIONS: Longitudinal study of microbioma profile allows early identification of patients at risk for major transplant-related complications such as sepsis by GN-MDR or acute GvHD, offering a new tool for individualized pre-emptive or therapeutical strategies to improve the outcome of allo-HSCT. Disclosures Ciceri: MolMed SpA: Consultancy.

Patients with advanced refractory Hodgkin Lymphoma (HL) may obtain long-term cure from haploidentical SCT. We experienced a package of haploidentical peripheral blood stem cell transplantation after Treosulfan-based conditioning and Rapamycin GvHD prophylaxis. Between July 1999 and June 2016, 57 patients with classical relapsed/refractory Hodgkin Lymphoma underwent an allogeneic stem cell transplantation (alloSCT) at san Raffaele Scientific Institute in Milan (Italy). Eleven patients received a matched related donor alloSCT, 7 patients received a matched unrelated donor alloSCT, one patient underwent a double cord blood transplant and 38 patients, lacking identical related or unrelated donor, received an haploidentical transplant (haploSCT); 32 out of 38 patients underwent an unmanipulated peripheral blood stem cell transplant. This retrospective study analyzes the outcome of these 32 patients allografted after a Treosulfan based conditioning and a backbone GvHD prophylaxis with the mTOR inhibitor Rapamycin. Median age at alloSCT was 30 years; twenty patients (62,5%) had a primary refractory disease. Median number of previous lines before haploSCT was 4 (range 2-8); thirty patients (94%) received at least one or more autologous stem cell transplant and 12 of them were considered in an auto-allo program. Median time from diagnosis to haploSCT were 30 months (range 8-146). At haploSCT after receiving the last salvage treatment, 10 patients were in complete remission (CR), 6 were in partial remission (PR) and 16 patients had progressive disease (PD). A combination of Melfalan or Thiotepa or TBI4Gy to Treosulfan mieloablative conditioning regimens (MAC) were used in 16 (50%) patients; the others received a Treosulfan-alone based reduced intensity conditioning regimen (RIC). GvHD prophylaxis consisted of in vivo T cell depletion with pre transplant anti-Thymocyte Globulin (ATG) in 19 patient and of post transplant Cyclophosphamide (PT-Cy) in 13 patients; all patients received also Mycophenolate Mofetil till day + 30 and Rapamycin till day + 90. Median numbers of infused CD34+/Kg were 5,4 x 10^6 (range 5-5,8) and median numbers of infused CD3+/Kg were 2.34 x 10^8 (range 1.00-4.76). Median follow up was 46 months (range 1-109); two and 4 years Overall survival (OS) was 52% and 48% respectively, Progression Free Survival (PFS) and Relapse Incidence (RI) were 29% and 59% at both two and four years. Transplant related mortality was 9.5% at 100 days, 13% at 1 year and for the entire follow-up. The 100-day Cumulative Incidence (CI) of grade ≥ 2 and grade ≥ 3 aGvHD were 31% and 19% respectively; CI of cGvHD was 38% and CI of moderate-severe cGvHD was 27% at both a 2 and 4 years. No difference in OS, PFS, RI were found if patients were stratified according to disease status at transplant or according to the use of ATG or PT-Cy. CI of cGvHD and CI of moderate-severe cGvHD were significantly better after RIC regimens vs MAC ones (p value 0.01 and 0.001 respectively), but no difference were found between the two groups in term of OS, PFS and RI. Twelve out of twenty-two patients with active disease at haploSCT achieved a CR after transplantation and median time from aploSCT to CR was 3 months (range 2-6); six of them (4 PD and 2 PR at transplant) achieved and maintained a CR for the entire follow-up without the need for other post transplant treatment. Unmanipulated peripheral blood haploSCT after Treosulfan based conditioning regimen and GvHD prophylaxis with Rapamycin is feasible, even in heavily pretreated patients and with active disease, with acceptable toxicities. Intensification of conditioning increased the toxicities. Disease relapse or progression was the major cause of treatment failure in our series, but 22 patients (69%) had detectable disease at the time of transplant. Six out of those very poor prognosis patients (28%) achieved a long term CR. Hodgkin Lymphoma is characterized by high mTOR activity, and Rapamycin is known to inhibit in vitro and in vivo cell proliferation and to induce apoptosis in Lymphoma cells. Rapamycin in these patients could have played an important role in disease control in immediate post transplant phase by increasing the apoptotic effect of chemotherapeutic agents, until the onset of the Graft versus Lymphoma effect. Disclosures Bonini: Molmed SpA: Consultancy; TxCell: Membership on an entity's Board of Directors or advisory committees. Ciceri:MolMed SpA: Consultancy.

Introduction Voriconazoleis a second-generationtriazolebroad-spectrum antifungal agent indicated in adults and children aged 2 years and above as treatment of invasive aspergillosis, treatment ofcandidaemiain non-neutropenic patients (pts), treatment of fluconazole-resistant serious invasive Candida infections, treatment of serious fungal infections caused byScedosporiumspp. and Fusarium spp. Voriconazoleis associated with a broad spectrum of dermatologically adverse reactions: it seems to be responsible for a multistep process beginning with acute and chronicphototoxicity, followed by actinic keratosis (AK), and finally skin squamous cell carcinoma (SCC), especially if therapy is maintained. Strictphotoprotectionis mandatory; drug replacement by anothertriazolemust be discussed in case of acutephototoxicity.Voriconazolemust be stopped in pts with chronicphototoxicity, and a long-term dermatologic follow-up of skin lesions is required even after withdrawal. It is now established thatvoriconazoleis an independent risk factor for the development of cutaneous malignancy in lung transplant recipients. Recently, a retrospective study from the Mayo Clinic (WojenskiDJ et al, Transplant Infectious Disease 2015, 17, 250-58) confirmed the association betweenvoriconazoleand SCC also after allo-HSCT (allogeneic hematopoietic stem cell transplantation) and identified cumulative days ofvoriconazoleas a risk factor for SCC. Methods The current study seeks to analyze the correlation betweenvoriconazoleexposure and non-melanoma skin cancer (NMSC) in our Center, where it is available an intensive dedicated follow-up after allo-HSCT to prevent and early detect second solid tumors. Results We analyze data prospectively collected at our Long-Term Follow-Up clinic between 2011 and 2016 including 302 adult pts with a minimum follow-up of 24 months. A written consent was given by pts allowing the use of medical records for research in accordance with the Declaration of Helsinki. Baseline characteristics of the 302 pts are outlined in table 1. In total, 25 pts developed NMSC - median time from allo-HSCT 42 months (range, 9 months - 20 years) - median follow-up after NMSC diagnosis 2 years (range, 2 months - 12 years). The estimated cumulative incidence of NMSC at 3 years was 3.2% and at 5 years 6.2%. At the dermatological annual evaluation 3 pts were presenting AK, only one progress to basal cell carcinoma (BCC), the 2 pts with AK are under dermatological follow-up. All pts were treated withvoriconazolefor more than 180 days. In total 19 pts were diagnosed with BCC and 6 pts with SCC. Five pts with SCC and 17 with BCC were treated withvoriconazole, overall 16/22 (4 SCC) for more than 180 days. All pts were treated according to standard practice for NMSC, unfortunately 1 pts deceased due to SCC progression. Only 2 pts were diagnosed and treated for NMSC before transplantation. Six pts had antecedent acute GvHD and 8 pts had antecedent moderate to severe chronic GvHD. History ofvoriconazoleexposure, cumulative days ofvoriconazoleuse, gender, age at transplant, TBI based conditioning regimen, acute/chronic GvHD and skin cancer pre-transplant were considered for analysis. Age at transplant above 48 years (p Conclusions Our experience confirms the correlation betweenvoriconazoleand occurrence of NMSC after allo-HSCT. Incidence of NMSC is higher than previously reported in registry reports, and the occurrence of NMSC in pts exposed tovoriconazoleseems to be precocious. This observation confirms the relevance of counseling and prevention of NMSC in patients benefiting fromvoriconazoleas a crucialmold-active antifungal prophylaxis and treatment. Disclosures Bonini: Molmed SpA: Consultancy; TxCell: Membership on an entity's Board of Directors or advisory committees. Ciceri:MolMed SpA: Consultancy.

Introduction Tyrosine kinase inhibitor (TKi) has become the standard of care in patients (pts) with chronic myeloid leukemia (CML) and an unavoidable tool in the combined therapy for pts with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Nevertheless, because of resistance to TKI and side-effects, allogeneic stem cell transplantation (HSCT) remains the standard therapy of ALL Ph+ and of CML pts failing 1st line therapy with TKi, with failure or insufficient response or intolerance or mutations resistant to 2nd generation TKI, or in the advanced phase at diagnosis (accelerated phase and blast crisis). Unfortunately, despite greater remission with the use of TKi pre-transplant, HSCT transplant outcome have not improved largely due to high incidence of relapse after transplant. In the past decade several multi-institutional studies confirmed the feasibility and safety of post-HSCT imatinib administration as prophylactic or therapeutic strategy. Second and 3rd generation TKi administration after HSCT - targeting mutational status and according to pre-HSCT activity - is today under investigation. Methods Here we are reporting our experience in post-HSCT treatment with the 3rd generation TKi ponatinib in 5 pts (4 CML, 1 ALL Ph+) treated between 2011 and 2016 at our Institution. Pts data and information were collected from Institutional database and chapters revision. A written consent was given by pts allowing the use of medical records for research in accordance with the Declaration of Helsinki. Results Pts and diseases features are reported in table 1. Stem cell source was peripheral blood in all cases, 3 pts were transplanted from a family mismatched donor (haplo), 1 from a family matched donor, 1 from a matched unrelated donor (MUD). The 3 haplo-transplanted pts previously underwent a MUD HSCT. All pts received a treosulfan based conditioning regimen and GvHD prophylaxis consisted on co-administration of MMF and rapamycin. Pre-transplant treatment for the ALL Ph+ consisted of chemotherapy combined with dasatinib, followed by a first MUD HSCT and dasatinib in maintenance. The patient relapsed 1 year after HSCT with documentation of mutation V299L. Ponatinib was introduced as salvage treatment to bridge second haplo HSCT. Pre-transplant treatment for the CML patients consisted of TKi therapy with combination of chemotherapy in case of uncontrolled progression of disease. Two pts received a first MUD HSCT but relapsed respectively 5 months and 4 years later. Four pts received ponatinib 45 mg daily before the last HSCT: one patient achieved sustained major molecular response, 3 pts obtained transient response. All pts were presenting 2nd generation TKi resistant mutation (ref table 1). Ponatinib was started at a median time of 157 days after HSCT (range, 117-583): in 3 cases as salvage treatment in overt relapse, while in one case as prophylaxis and one case as preemptive therapy. Acute GvHD was diagnosed in 4 pts before ponatinib administration, 2 of them also experienced chronic GvHD. No new cases of GvHD were observed after initiation of ponatinib. Immunosuppressive treatment and azoles treatment were discontinued before ponatinib in all but one patient who was under combined treatment for chronic GvHD: therapeutic drug monitoring was closely performed without evidence drug-drug interaction. Pts were regularly evaluated for toxicities. No serious adverse events were reported in our experience: we administered ponatinib at a median maximum dosage of 30 mg daily (range, 15-45 mg), for a median of 24 weeks (range, 4 - 116 weeks). Two pts required anti hypertension drugs. One patient was closely monitored for multifactorial liver cholestasis never requiring ponatinib discontinuation. At last evaluation one patient maintained the status of molecularly undetectable leukemia (follow-up post HSCT 30 months) and two pts obtained molecular response (follow-up post HSCT 25 months and 5 months). Two patients who received therapeutic ponatinib in overt relapse didn't respond and died for progressive disease. Conclusions Ponatinib is safe and well tolerated as bridge to HSCT and to maintain the disease control after transplant. Prophylaxis targeted therapy and pre-emptive therapy with ponatinib may lead the reduction of disease relapse for high-risk Ph+ leukemia. Disclosures Bonini: Molmed SpA: Consultancy; TxCell: Membership on an entity's Board of Directors or advisory committees. Ciceri:MolMed SpA: Consultancy.